A recent study by the U.S. Centers for Disease Control and Prevention found that keeping the middle seats open on airplanes offered some protection against the spread of COVID-19.
The CDC report stated that sitting two places from an infectious person could reduce a passenger's risk of exposure to "viable virus" particles by 23% compared with their risk sitting right next to a contagious person with their mask off.
Researchers found that the risk could be reduced by 57% in a three-row section with vacant middle seats.
Researchers added that more tests are needed to manage the virus's risk of possibly being transmitted and causing illness on planes.
Delta is set to reopen middle seats up to passengers beginning May 1.
New guidance from the CDC says fully vaccinated people can travel at low risk to themselves.